1. Field of the Invention
The present invention relates to an image pickup apparatus and a system utilizing the same, and more particularly to an image pickup apparatus and a system such as a digital camera, a video camera, a copying apparatus, and a facsimile apparatus.
2. Related Background Art
A solid-state image pickup apparatus formed by a one- or two-dimensional array of photoelectroc conversion elements such as photodiodes is widely employed in a digital camera, a video camera, a copying apparatus, a facsimile apparatus and the like. The solid-state image pickup apparatus includes a CCD image pickup device and an amplifying solid-state image pickup apparatus represented by a CMOS sensor which is formed integrally with peripheral circuits by a CMOS process.
Such solid-state image pickup apparatus shows a trend toward a larger number of pixels, with a decrease in the area of a photodiode, as a result of a reduction in the area of a pixel. It is therefore required to handle a signal charge of a smaller amount, and it is therefore required to reduce a dark current constituting a noise component, and to increase an effective area of the photodiode. For such purpose, EP 1017106A1 discloses in FIG. 4 (corresponding to Japanese Patent Application Laid-open No. 2000-232216) a configuration in which floating diffusion regions formed for every pixels are connected by a conductor, and in which the signal reading is executed by an amplification by a common amplifying MOS transistor, thereby reducing a number of transistors per unit pixel and maintaining the area of the photodiode larger.
Also when the solid-state image pickup apparatus becomes larger in the area, it becomes necessary, as disclosed in Japanese Patent Application Laid-open No. 2001-332714 (FIGS. 7 and 10) or Japanese Patent Application Laid-open No. 2001-230400 (FIGS. 1 and 16, corresponding to US 2001-1012133A) to form a well contact in order to obtain a firm substrate potential for the photodiode and the transistor and to suppress a shading phenomenon.
The present inventor has found that, in case of positioning a well contact between adjacent pixels, the dark current may become different between the adjacent pixels depending on a layout of conductive layers constituting electrodes and wirings.
Therefore, an object of the present invention is to provide a photoelectric conversion apparatus, a solid-state image pickup apparatus and a solid-state image pickup system, showing little difference in the dark currents in case of providing a well contact between adjacent pixels.